1. Field of the Invention
The present invention relates to an internal combustion engine that includes an engine main body configured by a crankcase and a cooling device equipped with a radiator cooled by cooling wind. The present invention also relates to a vehicle on which the internal combustion engine is mounted.
2. Background of the Invention
A cooling device of an internal combustion engine that includes a radiator cooled by the cooling wind is known from, for example, JP-A No. 2002-129960. In this known cooling device, a wind outlet portion for exhausting cooling wind that has passed through the radiator to the atmosphere is formed in a cylindrical shroud, coupled to the crankcase, for holding the radiator.
In order to enhance the cooling performance of the cooling water from the radiator, a radiator core of the radiator may be enlarged or a cooling fan may be enlarged to increase the wind volume of the cooling wind that passes through the radiator. However, this leads to an enlargement of the radiator and an enlargement of the cooling fan. Thus, consideration is made in increasing a passage area of the wind outlet portion formed in the shroud as a means for increasing the wind volume of the cooling wind. However, the shroud has limitations in terms of ensuring the rigidity of the shroud to support the radiator and an increase in the passage area of the wind outlet portion also has limitations. Thus, the increase in the wind volume of the cooling wind is also limited. Furthermore, when the internal combustion engine is a stationary type or when the vehicle mounted with the internal combustion engine is stopped, the cooling wind exhausted from the wind outlet portion close to the radiator sometimes again flows into the radiator, thereby lowering the cooling performance of the radiator.
In a vehicle mounted with an internal combustion engine, such as a vehicle in which the internal combustion is supported in a swinging manner by a vehicle body integrally with the wheels, enhancement of the cooling performance of the radiator by traveling wind cannot be expected too much when the radiator is arranged lateral to the engine main body, since the traveling wind is less likely to flow into the radiator. Thus, the wind volume of the cooling wind must be increased in order to enhance the cooling performance of the radiator.
Moreover, in a vehicle mounted with an internal combustion engine, the wind exhaust duct is sometimes preferably arranged so as to extend in the front and back direction instead of being arranged so as to extend in the left and right direction due to mounting modes of the internal combustion engine with respect to the vehicle body when increasing the wind volume of the cooling wind by exhausting the cooling wind (i.e., exhausted wind) passed through the radiator through the wind exhaust duct. In this case, however, the wind exhaust outlet portion of the wind exhaust duct becomes close to a fender that covers the wheels, and the fender sometimes inhibits smooth exhaust of the exhausted wind from the wind exhaust outlet portion. When the wind exhaust duct is arranged avoiding the fender, the wind exhaust duct enlarges, and furthermore, a compact arrangement becomes difficult.